Apparatus for perforating earth formations

ABSTRACT

This application discloses new and improved apparatus for perforating earth formations and then cleaning debris and the like from such perforations. As disclosed herein, the new and improved perforator of the present invention is provided with one or more pairs of like or similar perforating devices operatively arranged for producing perforations in an earth formation which are selectively directed so that each pair of perforations will be in fluid communication with each other. An enclosed lowpressure chamber is coupled to one of the perforating devices in each set and a seal is arranged around the perforating axis of this perforating device for at least limiting the direct entrance of well bore fluids into the perforation produced thereby. In this manner, upon operation of each pair of the perforating devices, well bore fluids will be drawn into the perforation produced by the other perforating device and be swept through the intercommunicating perforations into the low-pressure chamber for cleaning debris and loose formation materials from the perforations.

0 United States Patent [151 3,707,195 Lanmon, II [451 Dec. 26, 1972 [54] APPARATUS FOR PERFORATING Primary Examiner-David H. Brown EARTH FORMATIONS Attorney-Ernest R. Archambeau, Jr. et al.

[72] Inventor: C. P. Lanmon ll Friendswood,

Tex. [57] ABSTRACT This application discloses newand improved ap- [73] Asslgnee' z g gt gg g Corpon' paratus for perforating earth formations and then cleaning debris and the like from such perforations. [22] Filed: July 14, 1971 As disclosed herein, the new and improved perforator of the present invention is provided with one or more [21] Appl 162469 pairs of like or similar perforating devices operatively Related Application Data arranged for producing perforations in an earth format on which are selectively directed so that each pair of [62] Dmsm" 38,953, May 2 1970' Pat perforations will be in fluid communication with each 34530382- other. An enclosed low-pressure chamber is coupled to one of the perforating devices in each set and a seal [52] US. Cl ..l75/4.52, 166/100 is arranged around the perforating axis of this Pen [51] Illt. Cl. ..E2lb-43/ll6 forming device for at least limiting the direct entrance [58] Field of Search ..166/l00, 55.1; 175/452, 4.6 of we bore fluids into the perforation produced thereby. in this manner, upon operation of each pair [56] References d of the perforating devices, well bore fluids will be drawn into the perforation produced by the other per- UNITED STATES PATENTS forating device and be swept through the intercommu- 2,796,023 6/1957 Abendroth ..175/4. 52 nicating perforations into the low-pressure chamber 2,904,113 9/1959 McMahan @166! 100 for cleaning debris and loose formation materials from 3,305,032 2/1967 Schuster et a1. X the perforations; 3,347,314 10/1967 Schuster ..l66/ l00 X 15 Claims, 7 Drawing Figures PATENTEDmzs I972 SHEET 1 BF 2 C P Lanmon,11'

INVENTOR A TTORNEY PATENTED "E925 I973 3.707.195

SHEET 2 (IF 2 C PLanmon,H

F G. 5 INVENTOR ATTORNEY APPARATUS FOR PERFORATING EARTH FORMATIONS This application is a division of my copending application Ser. No. 38,953, filed May 20, 1970, now U.S. Pat. No. 3,630,282, for Methods And Apparatus For Perforating Earth Formations.

It is, of course, customary for a cased well bore to be perforated at one or more points to provide fluid communication with selected earth formations therearound. Once the well is perforated, various treating operations such as acidizing, fracturing, or sandconsolidating operations are typically conducted to prepare the well for efficient production. Those skilled in the art will appreciate, however, that it is not at all uncommon for one or more of the perforations along a given perforated interval to be at least partially blocked by loose formation materials, debris, as well as foreign matter which is usually deposited in a perforation by a typical shaped charge. A partial or total blockage of one or more of the perforations will, of course, impede or prohibit the introduction of treating fluids into those perforations and result in the inadequate treatment of at least those portions of the earth formation immediately adjacent thereto. As a result, further and otherwise needless treating operations will ultimately be required. Accordingly, unless all of the perforations along a perforated interval are capable of readily conducting fluids, subsequent treating operations as well as the production rate of the well will be significantly impaired.

Heretofore, substantial effort has been directed toward devising perforating apparatus and techniques for cleaning perforations in those situations where the formation to be perforated is substantially composed of loose or incompetent formation materials which must be chemically bonded to limit the subsequent production of these loose materials. For example, in US. Pat. No. 3,153,449, unique methods and apparatus are disclosed for producing a single perforation that is first flushed of loose formation materials and then injected with a suitable treating agent for consolidating the immediately surrounding portion of the formation. Similarly, US. Pat. No. 3,329,204, US. Pat. No. 3,347,314 and US. Pat. No. 3,347,315 respectively disclose new and improved techniques and tools for perforating a well casing at two closely spaced points and, after clearing the perforations of loose formation materials, injecting suitable consolidation agents. Although the several tools and techniques described in the aforementioned patents have been commercially employed, it will be appreciated that only one or, at best, two usable perforations are produced for each operation. Thus, if a formation interval of substantial length is to be perforated at several spaced points, tools such as these must be repetitively employed before the entire interval can be sufficiently perforated.

It will be appreciated, moreover, that none of these techniques or perforating tools are particularly suited for those situations where the formation that is to be perforated is competent and does not require the injection of a consolidating agent. Furthermore, with the possible exception of the techniques and tools disclosed in US. Pat. No. 3,305,018, little attention has been given heretofore for devising suitable procedures and perforating apparatus which are effective for perforating well-consolidated formations at a number of spaced locations and then cleaning the perforations in a single trip into a well bore.

Accordingly, it is an object of the present invention to provide new and improvedperforating apparatus for producing multiple debris-free perforations at spaced locations along a well bore interval traversing an earth formation irrespective of the competency of the formation.

This and other objects of the present invention are attained by arranging multiple sets of similar or like perforating devices as spaced intervals along a supporting carrier, with the perforating devices in each set being cooperatively directed so that their perforating axes will converge or at least approach an intersection within an earth formation ahead of the carrier. Means are further provided for enclosing one of the perforating devices in each set and fluidly coupling the enclosure surrounding the selected device-to an enclosed chamber which is initially unfilled and is maintained at a pressure less than that of the fluids in the well bore adjacent to a formation that is to be perforated in accordance with the methods of the present invention. New and improved sealing means are operatively arranged on the carrier and adapted, upon movement of the carrier to a selected positionin a well bore, for at least substantially blocking the direct entrance of well bore fluids into the enclosures associated therewith whenever the selected perforating devices are operated. New and improved biasing means are also provided for urging the sealing means into engagement with the well bore wall. In this manner when the new and improved perforating apparatus is employed, operation of the perforating devices in each set will produce perforations in the formation which will be effectual for establishing fluid communication so that well bore fluids will sweep through the circuitous passage defined in the formation by the cooperatively directed perforations for flushing debris and the like therefrom and into the enclosed chamber.

The novel features of the present invention are set forth with particularity in the appended claims.-The invention, together with further objects and advantages thereof, may be best understood by way of the following description of exemplary apparatus employing the principles of the invention as illustrated in the accompanying drawings, in which:

FIG. 1 depicts a preferred embodiment of perforating apparatus incorporating the principles of the present invention as this apparatus will appear positioned in a well bore while conducting a perforating operation;

FIG. 2 is an enlarged cross-sectioned elevational view of a portion of the perforating apparatus depicted in FIG. 1;

FIG. 3 is a cross-sectional view taken along the lines 3-3 ofFIG. 2;

FIG. 4 is an enlarged view of another portion of the perforating apparatus shown in FIG. 1;

FIG. 5 is a cross-sectional view taken along the lines 5-5 of FIG. 4; and

FIGS. 6 and 7 respectively depict the production of one pair of perforations with the new and improved apparatus of the present invention.

Turning now to FIG. 1, new and improved perforating apparatus arranged in accordance with the present invention is shown suspended in a typical manner from an electrical cable 11 within a casing 12 that is secured within a borehole 13 by a column of cement 14. The suspension cable 11 is spooled from a winch (not shown) at the earths surface that is adapted for selectively moving the perforating apparatus 10 through the casing 12 to bring the apparatus into position adjacent to an earth formation 15 which is to be perforated. Y

The perforating apparatus 10 of the present invention includes an elongated body or carrier 16 which is conveniently arranged as a series of housing sections, as at 17-19, which are coupled to a plurality of tandernly arranged perforating units as at and .21 for performing a'given perforating operating. As is typical,

suitable depth-indicating means, such as a casing-collar locators, is arranged in one of the sections as at 17; and, in the preferred embodiment of the apparatus 10, another section 18 of the carrier 16 is appropriately arranged for enclosing an electrical control system such as that shown in US. Pat. No. 3,327,791 for selective operation of the perforating apparatus. For reasons that will subsequently be explained in greater detail, positioning means, such as rearwardly-acting opposed springs 22-25 of a new and improved design, are mounted adjacent to the upper and lower ends of the carrier 16 and cooperatively arranged for urging the carrier forwardly to maintain the forward faces of a plurality of sealing means, as at 26, respectively mounted on each of the perforating units 20 and 21 in continuous sliding engagement with the adjacent wall of the casing 12. I

Turning now to FIG. 2, an enlarged view is shown of the upper perforating unit 20 which is similar or identical to the other units, as at 21, coupled therebelow. In the illustrated preferred embodiment of the present invention, a cylindrical body 27 is arranged to include two longitudinally spaced lateral chambers 28 and 29 which are respectively proportioned to enclose perforating means, such as a shaped charge as at 30 and 31. vin keeping with the objects of the present invention, the shaped charge chambers 28 and 29 are respectively formed about laterally directed axes 32 and 33, with the axis of the upper chamber being tilted downwardly to converge and, preferably, intersect the axis of the lower chamber at a selected distance ahead of the forward face (to the right as viewed in FIG. 2) of the body 27. A third chamber 34 of a predetermined volume is formed in the lower portion of the body 27 and fluidly coupled to the intermediate chamber 29 as by an interconnecting passage 35 in the body.

Although other coupling arrangements can, of course, be provided for the several perforating units 20 and 21, it is preferred to arrange each unit with a reduced-diameter upper end, as at 36, that is sealingly fitted, as by an O-ring 37, into the chamber 34 in the unit thereabove to close the lower end of the chamber. By means of suitable screws, as at 38, the perforating units 20 and 21 can be secured together and properly oriented to accurately direct their respective shaped charges 30 and 31 forwardly of the carrier 16. in the preferred embodiment of the tool 10, a removable plug, as at 39, is provided for draining the chamber 34 through a suitable port 40. It will, of course, be recognized that the lowermost section 19 of the carrier 16 is appropriately arranged to close the lower chamber (as at 34 in the unit 20) in the lowermost perforating unit. Similarly, the housing section '18 is appropriately arranged to sealingly receive the upper end portion of the upper perforating unit 20.

To gain access to the upper chamber 28, an enlarged lateral port 41 of sufficient size topermi't the introduction of the shaped charge 30 into the chamber is arranged in a downwardly and inwardly inclined flat surface 42' formed transversely across the forward wall of the body 27 and, preferably, perpendicularly intersecting the inclined lateral axis 32. A port-closure plug 43 is secured in the port 41, as by threads 44, and cooperates with a sealing member 45 for fluidly sealing the shaped charge 30 within the upper chamber 28. In a similar fashion, a flat transverse surface 46 is formed across the forward wall of the body 27; and a lateral port 47 therein is coaxially arranged about the axis 33 and suitably sized for admitting the shaped charge 31 into the intermediate chamber 29.

Although the shaped charges 30 and 31 may, of course, be of other designs, it is preferred that they be similar or identical to those disclosed in US. Pat. No.

3,329,218. Accordingly, as fully explained in that patent, lateral bores 48 and 49 are respectively provided in the rear wall of the body 27 in coincidental alignment with the perforating axes 32 and 33 and appropriately arranged for respectively receiving electrical contactors 50 and 51 (such as those shown at 28 in the aforementioned patent) and detonating means such as electrically actuated initiators 52 and 53 (such as those shown at 44 in the aforementioned patent) to enable the shaped charges 30 and 31 to be selectively detonated from the surface by operation of the control system in the carrier section 18. Inasmuch as the particular details of the shaped charges 30 and 31 and their respective detonators or initiators 5 2 and 53 are of no significance to the present invention, further description is unnecessary.

Turning now to the new and improved sealing means 26 of the present invention. As best illustrated in FIGS. 2 and 3, the access port 47 is preferably threaded, as at 54, for cooperatively receiving the rearward portion of a closure member 55 having an elongated forward tubular portion 56 and an intermediate shoulder or outwardly enlarged flange 57 adapted for engagement against the flat surface 46. A sealing member 58 is cooperatively arranged to fluidly seal the closure member 55 in relation to the body 27. To prevent the entrance of well fluids into the intermediate chamber 29 until the shaped charge 31 therein is detonated, a transverse web, as at 59, is arranged across the forward tubular portion 56 and, preferably, positioned at the extreme forward end thereof. Although it could alternatively be made integral with the closure member 55, a separate tubular member 60 is coaxially fitted over the forward portion 56 of the closure member and, for reasons that will subsequently be explained, extended forwardly thereof a sufficient distance to at least project beyond the curvature of the forward wall of the body 27.

In the preferred embodiment of the sealing means 26, an annular sealing pad 61 of a sturdy elastomeric material is coaxially fitted over the tubular extension 60 and secured to the fiat body surface 46. Although the initial configuration of the forward face of the sealing pad 61 is not critical in accomplishing the objects of the present invention, it is preferred to initially shape the forward face of the sealing member (as best seen in FIG. 3) to substantially conform to the curvature of the internal wall of the casing 12. Where this is done, the tubular extension 60 is preferably arranged with a hexagonal exterior surface adapted for complementally fitting within the axial bore through the sealing pad 61 so as to prevent it from turning thereon out of its initial angular position. To prevent the sealing member 61 from being dislodged from the body 27 as the perforating apparatus is being moved into position in the well bore 13, the sealing member is provided with an outwardly enlarged portion 62 which is overlayed by an annular retainer 63 and secured to the body 27 as by one or more screws (not shown). lt will be appreciated, therefore, that once the shaped charge 31 is enclosed within the intermediate chamber 29 and the closure member 55 and the sealing member 61 and the tubular extension 60 are respectively secured to the body 27, only the forwardmost portions of these latter two members will contact the inner wall of the casing 12 whenever the perforating apparatus 10 is urged theretoward by the upper and lower positioning springs 22-25.

It should be noted that longitudinally disposed bow springs could be substituted for the new and improved positioning springs 22-25 without unduly affecting the unique operation of the remainder of the perforating apparatus 10. Those skilled in the art will recognized, however, that it will often be necessary to introduce the perforating apparatus 10 into a well bore by way of pressure-control equipment at the surface such as blowout preventors, so-called lubricators," and similar restrictions. Thus, typical bow springs which can be readily collapsed to pass such restrictions and still becapable of developing spring forces of the same magnitude as the new and improved positioning springs 22-25 would be objectionably long. Accordingly, in the preferred embodiment of the new and improved positioning springs 22-25 of the present invention, each spring is respectively comprised of a generally flat sheet of a somewhat-resilient material such as spring steel or the like which will readily flex. As best seen in FIG. 1, the forward edge of each of the several springs 22-25 is secured longitudinally along one or the other sides of the carrier 16, as by screws 64 and 65, so that the unrestrained or cantilevered portion of each spring will initially extend well behind the rear wall of the carrier. It will be noted, therefore, that by longitudinally offsetting the upper springs 22 and 23 and mounting the springs on alternate sides of the carrier 16 as illustrated in FIGS. 1 and 3, each of these springs can be transversely flexed so as to curve it back around the rear of the carrier. The lower springs 24 and 25 are similarly arranged for functioning in the same new and improved manner. The transverse deflections of the positioning springs 22-25 will, of course, impose forwardly acting spring forces on the carrier 16 which are commensurate with the material employed, the extent of their deflection, as well as their physical dimensions.

Accordingly, when the new and improved perforating apparatus 10 is first being lowered into the well bore 13, the upper and lower springs 22-25 are manually flexed inwardly and back around the rear of the carrier 16 as required for introducing the perforating apparatus into the casing 12 at the surface of the earth. The, as best seen in FIG. 3, once the perforating apparatus 10 is disposed within the casing 12, each of the new and improved springs 22-25 will assume a generally arcuate curvature around the rear. of the carrier 16 so that their longitudinal rearward edges, as at 66 and 67, will respectively contact the wall of the casing behind the carrier and somewhat on the opposite side thereof from where that particular spring is secured. Thus, by virtue of the alternate disposition of the springs 2225 along the rear of the carrier 16, the carrier will be reliably positioned within the casing 12 so that as the tool 10 is lowered into the well bore 13 the forwardmost portions of the extension members 60 and the sealing pads 61 will always be urged squarely against the adjacent wall of the casing.

Accordingly, in view of the continued abrasion of the casing 12 against the sealing member 61 and the tubular extension 60 of each of the perforating units 20 and 21 as the perforating apparatus 10 is moved into position adjacent to the earth formation 15, the sealing members and their associated tubular extensions will be progressively ground or lapped to complementally fit the curvature of the casing. In this manner, it will be assured that by the time the perforating apparatus 10 is positioned adjacent to the earth formation 15, at least the forward end of the tubular extension 60 and the forward face of the elastomeric sealing member 61 will closely conform to the internal configuration of the casing 12.

It will be appreciated, however, that the amount of material that will be progressively abraded from the tubular extension 60 and the sealing member 61 of each of the several perforating units as at 20 and 21 will, for the large part, be directly related to the distance which the perforating apparatus 10 moves through the well bore 13. For example, in a relatively shallow well, the amount of wear experienced by the tubular extensions 60 and the sealing members 6 1 will be correspondingly slight. On the other hand, should the earth formation 15 be at a substantial depth in the well bore 13, the tubular extensions 60 as well as the forward faces of the sealing members 61 might well be unduly worn by the time that the perforating apparatus 10 has finally reached its final position.

Accordingly, as best seen in FIGS. 4 and 5, to limit the amount of wear or abrasion to which the several sealing members 61 and the tubular extensions 60 will be subjected, upper and lower pairs of forwardly projecting lugs, as at 68 and 69, are respectively arranged near the upper and lower ends of the carrier 16 to prevent these several members from being excessively abraded by the time the perforating apparatus 10 is adjacent to the formation 15. It will be recognized, of course, that the wear-limiting lugs 68 and 69 will be arranged to allow the sealing members 61 and the tubular extensions 60 to always be sufficiently abraded to closely fit the curvature of the internal wall of the casing 12. In the preferred manner of accomplishing this, each of the several wear-limiting lugs 68 and 69 is comprised of a small block 70 of a hardened or abrasion-resistant material such as tungsten carbide or the like that is secured as by screws 71 to the carrier 16. The forward upright edges of each of the several hardened blocks, as at 70, are cooperatively positioned at a predetermined distance away from the forward face of the carrier 16 so that, once the sealing members 61 and the tubular extensions 60 have been sufficiently ground down to assure that their forward surface complementally fit the curvature of the casing 12, the several blocks will substantially limit, if not altogether prevent, further abrasion. of the sealing members and the extensions. To protect the blocks 70 from striking inward projections in the casing 12 as the tool is being moved therein, shoulders as at 72 are preferably provided above and below the blocks.

As an added feature of the present invention, it will be appreciated that the perforating apparatus 10 can be normally expected to be employed in various sizes of easing. Accordingly, to permit a ready adjustment of the guides 68 and 69, each of the several blocks 70 is adapted to be selectively secured in one of at least two predetermined positions in relation to the carrier 16. To facilitate the placement of the blocks 70 in these predetermined positions, selectively arranged seating surfaces, as at 73 and 74, are formed at appropriate positions on the carrier 16 so that each of the hardened blocks can be readily secured to accurately position their outer edges at the correct position for sliding engagement with the inner wall of a given casing size once the sealing pads 61 and the tubular extensions 60 are lapped into conformity with the casing wall.

Referring again to FIG. 1, it will be appreciated that once the perforating apparatus 10 is moved into position adjacent to the formation 15, the perforating units as at 20 and 21 are in readiness for perforating the easing 12 and the cement 14' to gain access to the earth formation. Thus, as best seen in FIG. 6, upon detona tion of the shaped charge 30 in, for example, the upper perforating unit 20, a perforation 75 will be produced along the axis 32 into the adjacent earth formation 15. The detonation of the upper shaped charge 30 will produce a perforating jet which, as is well known in the art, will leave debris such as a slug. 76 in the forward portion of the perforation 75 as well as a relatively impermeable sheath or layer of debris as at 77 along the walls of at least a substantial portion thereof.

Accordingly, in keeping with the objects of the present invention, detonation of the second shaped charge 31 in the perforating unit 20 will, as depicted in FIG. 7, produce a perforation as at 78 which substantially intersects the first perforation 75 so as to form a circuitous passage in the formation through which the fluids in the well bore 13 can enter the enclosed low-pressure chamber 34 in the perforating unit. Thus, as schematically indicated by the arrows 79, once the perforating jet produced by the second shaped charge 31 pierces the transverse barrier 59 and produces the second perforation, the well bore fluids will ruch into the low-pressure chamber 34 by way of the intersecting perforations 75 and 78. It will be appreciated,'therefore, that the rapid flow of these fluids 79 will flush the debris (as at 76 and 77) from the first perforation 75 as well as similar debris (not'shown) in the second perforation 78. Moreover, it is believed that the sudden inrush of the well bore fluids will also be effective for removing any loose formation materials in both of the forations 75 and 78 will be achieved by the use of theperforations and 78 so that, once they are enlarged as depicted, the flowcapabilities of the perforations will be significantly improved over what would otherwise be expected for perforations produced by prior perforating techniques.

it should be noted that the competency of the formation 15 will, of course, largely determine the degree of enlargement of the perforations 75 and 78 that will result from the rapid influx of the well bore fluids therethrough. Thus, should the formation 15 be relatively unconsolidated, it is expected that a substantial cavity will be formed (such as depicted at 88 in US. Pat. No. 3,347,314). In any event, therefore, a significant improvement in the flow characteristics of the perapparatus of the present invention.

It should be noted that the sequence of firing the several perforating units as at 20 and 21 as well as their respective shaped charges 30 and 31 is flexible. The control system in the housing section 18 can, of course, be adapted to actuate the perforating units as at 20 and 21 in any desired order either in groups or individually. Similarly, the shaped charges 30 and 31 in any of the several perforating units as at 20 and 21 can be selectively detonated either in any order or simultaneously. Thus, it will be appreciated that the perforating apparatus 10 of the present invention is readily suited for any perforating operation.

As previously described, the cooperative relationship of the wear-limiting lugs 68 and 69 and the several sealing means 26 will assure that the forward end of each of the tubular extensions 60 will be lapped or ground down so as to closely conform to the curvature of the casing 12 once the perforating apparatus. 10 is adjacent to the formation 15. Thus, it is believed that the sealing pads 61 may not necessarily be essential since, at best, there could only be an insignificant flow of well bore fluids through whatever minute gap might be present between the casing wall and the well-lapped forward end of the tubular extensions 60. it is, however, preferred to include the sealing pads 61 with the sealing means 26 as a preventative measure since the forward ends of one or more of the tubular extensions 60 might be damaged as the perforating apparatus 10 is moved through the casing 12.

Accordingly, it will be appreciated that the present invention has provided new and improved apparatus for producing multiple perforations in earth formations of various degrees of competency and then cleaning these perforations to assure improved flow communication between the well bore and the perforated formations. By arranging the sealing members along the forward wall of the perforator and urging these members into sliding contact with the casing wall, the forward faces of the sealing members will be lapped to closely fit the internal curvature of the casing as the perforator is moved into position in the well bore. Moreover, .by virtue of this lapping action, discrepancies in the longitudinal alignment of the seals on the several perforating units will be corrected. Thus, once the perforating apparatus is positioned, detonation of the several pairs of shaped charges will produce a corresponding number of intercommunicating flow passages in the formation between the well bore fluids and the initially enclosed chambers for inducing a rapid influx of these fluids through the flow passages to clear them of debris and other flow-blocking materials.

While a particular embodiment of the present invention has been shown and described, it is apparent that changes and modifications may be made without departing from this invention in its broader aspects; and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of this invention.

What is claimed is:

l. Perforating apparatus comprising: a body adapted for suspension in a well bore; sealing means mounted on the forward face of said body and projecting outwardly therefrom; a chamber in said body; perforating means enclosed in said chamber and directed along a selected lateral axis intersecting the forward face of said sealing means; and means responsive to passage of said body through a well casing for complementally shaping said forward face of said sealing means to fit the internal curvature of such a well casing and including spring means mounted on said body and operatively arranged for retaining said forward face of said sealing means in sliding engagement with such a well casing and with sufficient force to abrade saidsealing means as said body is moved into position in a well bore.

2. The perforating apparatus of claim 1 wherein said sealing means include a metallic chamber.

3. The perforating apparatus of claim 1 wherein said sealing means include an elastomeric sealing pad.

4. The perforating apparatus of claim 1 wherein said sealing means include a metallic member and' an annular elastomeric sealing pad mounted around said metallic member.

5. The perforating apparatus of claim 1 further including abrasion-resistant spacer means mounted on said body and extending forwardly of said forward face of said body a lateral distance somewhat less than the initial lateral distance between said forward face of said body and said forward face of said sealing means for limiting the degree of abrasion of said sealing means.

6. The perforating apparatus of claim 1 wherein said spring means include at least one pair of flat sheets of a spring material respectively mounted along opposite sides of said body and adapted to be arcuately curved around the rear face thereof for sliding engagement with angularly spaced locations on a well casing and to the rear of said body.

7. The perforating apparatus of claim 6 wherein said flat sheets are mounted at longitudinally spaced locations along said opposite sides of said body so that the free rearward edges of said flat sheets can be slidably engaged with angularly spaced locations on a well casing and to the rear of said body and which are respectively substantially opposite from that side of said body on which that flat sheet is mounted.

8. Perforating apparatus comprising: a body adapted for suspension in a well bore; sealing means mounted on the forward face of said body and projecting outwardly therefrom; a chamber in said body; first perforating means enclosed in said chamber and directed along a selected lateral axis intersecting the forward face of said sealing means; second perforating means arranged on said body exterior of said chamber and directed along an axis approaching an intersection with said lateral axis ahead of said sealing means; and means responsive to passage of said body through a well casing for complementally shaping said forward face of said sealing means to fit the internal curvature of such a well casing and including spring means mounted on said body and operatively arranged for retaining said forward face of said sealing means in sliding engagement with such a well casing and with sufficient force to abrade said sealing means as said body is moved into position in a well bore.

9. The perforating apparatus of claim 8 further includingabrasion-resistant spacer means mounted on said body and extending forwardly of said forward face of said body a lateral distance somewhat less than the initial lateral distance between said forward face of said body and said forward face of said sealing means for limiting the degree of abrasion of said sealing means.

10. 'The perforating apparatus of claim 8 wherein said spring means include at least one pair of flat sheets of a-spring material respectively mounted along opposite sides of said body and adapted to be arcuately curved around the rear face thereof for sliding engagement with angularly spaced locations on a well casing and to the rear of said body.

11. The perforating apparatus of claim 10 wherein said flat sheets are mounted at longitudinally spaced locations along said opposite sides of said body so that the free. rearward edges of said flat sheets can be slidably engaged with angularly spaced locations on a well casing and to the rear of said body and which are respectively substantially opposite from that side of said body on which that flat sheet is mounted.

12. Perforating apparatus comprising: a body adapted for suspension in a well bore; a plurality of sealing members mounted at spaced intervals along the forward face of said body and projecting outwardly therefrom; a plurality of chambers arranged at spaced intervals along said body; a plurality of first perforating devices individually enclosed in each of said chambers and respectively directed along a selected lateral axis intersecting the forward face of the sealing member adjacent thereto to produce first perforations through a well casing which are isolated from well bore fluids by said sealing members; a plurality of second perforating devices mounted on said body exterior of said chambers, each of said second perforating devices being directed along an axis approaching an intersection with the lateral axis of the first perforating device adjacent thereto at a point ahead of the sealing means associated therewith to produce second perforations intersecting said first perforations and which are exposed to well bore fluids; and spring means on said body adapted for complementally engaging said sealing members with a well casing to isolate said first perforations without blocking fluid communication between well bore fluids and said second perforations.

13. The perforating apparatus of claim 12 further including upper and lower abrasion-resistant spacer means mounted at longitudinally spaced intervals along said body and respectively extending forwardly of said forward face of said body a lateral distance somewhat less than the initial lateral distance between said forward face of said body and said forward faces of said sealing members for limiting the extent of abrasion of said sealing members upon passage of said perforating apparatus through a well bore.

14. The perforating apparatus of claim 12 wherein said spring means include first and second pairs of flat sheets of a spring material respectively mounted at spaced intervals along opposite sides of said body and adapted to be arcuately curved around the rear face thereof for sliding engagement with angularly spaced locations on a well casing and to the rear of said body.

15. The perforating apparatus of claim 14 wherein 

1. Perforating apparatus comprising: a body adapted for suspension in a well bore; sealing means mounted on the forward face of said body and projecting outwardly therefrom; a chamber in said body; perforating means enclosed in said chamber and directed along a selected lateral axis intersecting the forward face of said sealing means; and means responsive to passage of said body through a well casing for complementally shaping said forward face of said sealing means to fit the internal curvature of such a well casing and including spring means mounted on said body and operatively arranged for retaining said forward face of said sealing means in sliding engagement with such a well casing and with sufficient force to abrade said sealing means as said body is moved into position in a well bore.
 2. The perforating apparatus of claim 1 wherein said sealing means include a metallic chamber.
 3. The perforating apparatus of claim 1 wherein said sealing means include an elastomeric sealing pad.
 4. The perforating apparatus of claim 1 wherein said sealing means include a metallic member and an annular elastomeric sealing pad mounted around said metallic member.
 5. The perforating apparatus of claim 1 further including abrasion-resistant spacer means mounted on said body and extending forwardly of said forward face of said body a lateral distance somewhat less than the initial lateral distance between said forward face of said body and said forward face of said sealing means for limiting the degree of abrasion of said sealing means.
 6. The perforating apparatus of claim 1 wherein said spring means include at least one pair of flat sheets of a spring material respectively mounted along opposite sides of said body and adapted to be arcuately curved around the rear face thereof for sliding engagement with angularly spaced locations on a well casing and to the rear of said body.
 7. The perforating apparatus of claim 6 wherein said flat sheets are mounted at longitudinally spaced locations along said opposite sides of said body so that the free rearward edges of said flat sheets can be slidably engaged with angularly spaced locations on a well casing and to the rear of said body and which are respectively substantially opposite from that side of said body on which that flat sheet is mounted.
 8. Perforating apparatus comprising: a body adapted for suspension in a well bore; sealing means mounted on the forward face of said body and projecting outwardly therefrom; a chamber in said body; first perforating means enclosed in said chamber and directed along a selected lateral axis intersecting the forward face of said sealing means; second perforating means arranged on said body exterior of said chamber and directed along an axis approaching an intersection with said lateral axis ahead of said sealing means; and means responsive to passage of said body through a well casing for complementally shaping said forward face of said sealing means to fit the internal curvature of such a well casing and including spring means mounted on said body and operatively arranged for retaining said forward face of said sealing means in sliding engagement with such a well casing and with sufficient force to abrade said sealing means as said body is moved into position in a well bore.
 9. The perforating apparatus of claim 8 further including abrasion-resistant spacer means mounted on said body and extending forwardly of said forward face of said body a lateral distance somewhat less than the initial lateral distance between said forward face of said body and said forward face of said sealing means for limiting the degree of abrasion of said sealing means.
 10. The perforating apparatus of claim 8 wherein said spring means include at least one pair of flat sheets of a spring material respectively mounted along opposite sides of said body and adapted to be arcuately curved around the rear face thereof for sliding engagement with angularly spaced locations on a well casing and to the rear of said body.
 11. The perforating apparatus of claim 10 wherein said flat sheets are mounted at longitudinally spaced locations along said opposite sides of said body so that the free rearward edges of said flat sheets can be slidably engaged with angularly spaced locations on a well casing and to the rear of said body and which are respectively substantially opposite from that side of said body on which that flat sheet is mounted.
 12. Perforating apparatus comprising: a body adapted for suspension in a well bore; a plurality of sealing members mounted at spaced intervals along the forward face of said body and projecting outwardly therefrom; a plurality of chambers arranged at spaced intervals along said body; a plurality of first perforating devices individually enclosed in each of said chambers and respectively directed along a selected lateral axis intersecting the forward face of the sealing member adjacent thereto to produce first perforations through a well casing which are isolated from well bore fluids by said sealing members; a plurality of second perforating devices mounted on said body exterior of said chambers, each of said second perforating devices being directed along an axis approaching an intersection with the lateral axis of the first perforating device adjacent thereto at a point ahead of the sealing means associated therewith to produce second perforations intersecting said first perforations and which are exposed to well bore fluids; and spring means on said body adapted for complementally engaging said sealing members with a well casing to isolate said first perforations without blocking fluid communication between well bore fluids and said second perforations.
 13. The perforating apparatus of claim 12 further including upper and lower abrasion-resistant spacer means mounted at longitudinally spaced intervals along said body and respectively extending forwardly of said forward face of said body a lateral distance somewhat less than the initial lateral distance between said forward face of said body and said forward faces of said sealing members for limiting the extent of abrasion of said sealing members upon passage of said perforating apparatus through a well bore.
 14. The perforating apparatus of claim 12 wherein said spring means include first and second pairs of flat sheets of a spring material respectively mounted at spaced intervals along opposite sides of said body and adapted to be arcuately curved around the rear face thereof for sliding eNgagement with angularly spaced locations on a well casing and to the rear of said body.
 15. The perforating apparatus of claim 14 wherein each of said flat sheets is longitudinally spaced in relation to the others of said flat sheets so that the free rearward edges of said flat sheets can be slidably engaged with angularly spaced locations on a well casing and to the rear of said body and which are respectively substantially opposite from that side of said body on which that flat sheet is mounted. 